TooledSteel

//Tooled Steel by Ivan DeWolf
// Modified 4/27/21 by Saul Espinosa for Redshift3d
// Added ACES output, min/max and page meta data and Coating Microfacet GGX Closure Layer
vector nearPtLine(
    point testLoc,
    point lineStart,
    point lineEnd)
{
    float lineMag = distance(lineStart, lineEnd);
    float U = dot(testLoc-lineStart, lineEnd - lineStart) / (lineMag * lineMag);
    return lineStart + U * (lineEnd - lineStart);
}
shader tooldSteel
[[  string help = "Machine Tooled Material Shader",
    string label = "Machine Tooled Steel" ]]
(
    color metal_color = color(0.9,0.8,0.7)
        [[
            string page = "0 : Metal",
            string label = "Metal Color"
        ]],
    float xalph = 1
        [[
            string page = "0 : Metal",
            string label = "Anisotropy Roughness x",
            float min =  0,
            float max = 1
        ]],
    float yalph = .1
        [[
            string page = "0 : Metal",
            string label = "Anisotropy Roughness y",
            float min =  0,
            float max = 1
        ]],
    float IOR = 15
        [[
            string page = "0 : Metal",
            float min =  1,
            float max = 25
        ]],
    float cellmult = 10
        [[
            string page = "0 : Metal",
            string label = "Scale",
            float min =  0,
            float max = 100
        ]],
    color coat_color = color(1.0)
        [[string label = "Coat Color",
        string page = "1 : Coat",
        ]],
    float coat_weight = 0.0
        [[string label = "Coat Weight" ,
        string page = "1 : Coat",
    float min = 0, float max = 1
        ]],
    float coat_roughness = 0.0
        [[string label = "Coat Roughness" ,
        string page = "1 : Coat",
    float min = 0, float max = 1
        ]],
    float coat_IOR = 1.52
        [[string label = "Coat IOR" ,
        string page = "1 : Coat",
    float min = 0, float max = 25
        ]],
    int   aces = 0
        [[
        string page = "2 : Extra",
        string widget = "checkBox",
        int connectable = 0,
        string label = "ACES"
        ]],
    output closure color outColor = 0.0)
{
    // ACES sRGB Transform
    matrix aces_tm = matrix(
        0.6131, 0.0701, 0.0206, 0,
        0.3395, 0.9164, 0.1096, 0,
        0.0474, 0.0135, 0.8698, 0,
        0, 0, 0, 1);
    color Out = metal_color;
    float r = Out[0], g = Out[1], b = Out[2];
    if (aces == 0)
    color attenColor = Out;
    else
    {
    attenColor = transform(aces_tm, vector(r,g,b));
    }    
    vector Normal = N;
    point Ploc = P;
    vector centerLoc = round(Ploc * cellmult)/cellmult;
    vector spinCenter = nearPtLine(Ploc, centerLoc+Normal, centerLoc -Normal);
    vector anisoDir = normalize(spinCenter-Ploc);
    outColor = attenColor * microfacet("ggx", Normal, anisoDir, xalph, yalph, IOR, 0) + (coat_color * coat_weight * microfacet("ggx",Normal,coat_roughness,coat_IOR,0));
}